Natural History and Biology of Skin Neurofibromas in Neurofibromatosis Type 1

This study will explore the growth of dermal neurofibromas (skin tumors) in patients with neurofibromatosis type 1 (NF1). Investigators will try to learn: 1) how fast (or slow) these benign tumors grow in NF1, 2) how often new tumors appear and 3) what genes are involved in the growth of the tumors. Men and women between 20 and 50 years of age diagnosed with NF1 and their biological parents are eligible for this study. Patients with NF1 are evaluated at the NIH Clinical Center with the following tests and procedures: * Medical examination and drawing of family tree. * Photos of the back, abdomen and thigh in order to count the number of skin tumors. * Photos of the skin taken with a special camera (Primos camera) that takes very detailed pictures of a small area of skin. * Photos of the skin taken with a dermatoscope, which takes very detailed pictures of a small area of skin under high magnification. * Biopsy of at least one skin tumor and biopsy of a small piece of normal skin. * Blood sample collection for genetic testing of the gene NF1 and to establish a cell line. * Other medical tests (e.g., x-rays or MRI) if needed. Patients and their families will also have a genetic counseling session and an opportunity to ask questions about neurofibromatosis type 1. Patients return to the NIH after 3, 6, 12, 18 and 24 months for follow-up photographs and possibly blood samples. Biological parents of patients provide a blood sample for genetic testing.